The present invention relates to a power source system including a power source and a multiphase converter.
Among vehicles that include an electric motor, for example, there are vehicles including a multiphase converter for converting a voltage. As a method of controlling the multiphase converter that includes a plurality of phases of which a controlled volume can be independently changed, a detecting device that detects a state of each phase such as a volume of current passing through each phase and a temperature in each phase, and a control unit that supplies a control signal for specifying a control volume relative to each phase, there is known a method of supplying a control signal for correcting the control volume for each phase based on a state of each phase detected by the detecting device (see Patent Document 1, for example). In this system, an efficient operation can be performed by increasing a passing volume of current as far as possible according to this state.    Patent Document 1: Patent Publication JP-A-2007-159315
However, when only efficiency is taken into account, a reactor and a semiconductor element part which includes electronic parts that constitute the multiphase converter become at excessively high temperatures.
Therefore, increasing the efficiency as far as possible is required while protecting the configuration parts of the multiphase converter, such as the reactor and the semiconductor part.